Spam virus warnings in my calendar app on iPhone

I have these warnings in my calendar that first started appearing when I visited a movie website and there is no options to delete or mute them, and more keep being made every few days. I don’t know what to do because I have tried following your previous advice about going to passwords and accounts and checking for unauthorised calendar accounts but I can’t find any and I don’t know where to go from here as they are still here and I’m getting worried. Help please.